Nicardipine vs Esmolol Craniotomy Emergence

Emergence hypertension is a common occurrence in patients emerging from general anesthesia. This elevation of arterial pressure is particularly concerning in patients undergoing craniotomy due to increased risk of morbidity and mortality in patients with altered intracranial elastance. Thus, identifying better methods to attenuate the hemodynamic changes associated with emergence from anesthesia can improve patient safety, especially in the neurosurgical patient. Study Hypothesis: Nicardipine is more effective than esmolol as a sole agent in maintaining blood pressure within goal range in the setting of emergence hypertension after craniotomy.

Emergence hypertension following craniotomy is a well-described, albeit poorly understood, phenomenon. Strict control of blood pressure is of utmost importance during and after neurosurgical procedures; failure to prevent acute rises in arterial blood pressure places patients at increased risk of intracranial bleeding, cerebral edema, increased intracranial pressure, and prolonged hospital stays. Emergence hypertension after craniotomy seems to be the result of an acute and transient increase in catecholamine release, peripheral vasoconstriction, and reduced baroreceptor sensitivity. Prior investigations have demonstrated that treatment with antihypertensive agents is required in 60 to 90% of neurosurgical patients postoperatively. Given the common occurrence of emergence hypertension after craniotomy and the increased risk of potentially devastating events that may occur in the setting of acute increases in arterial blood pressure, it is important to identify how best to manage these hemodynamic changes. An ideal drug for the management of emergence hypertension would be a short-acting, parenteral drug that is easily and rapidly titratable. Medications commonly utilized include nicardipine, labetolol, and esmolol. When given as a bolus, nicardipine, a calcium channel blocker, demonstrates a maximal response in <2 minutes and a mean half-life of approximately 40 minutes. Nicardipine is also frequently administered as an infusion; however, time to onset is increased if no bolus is administered and duration of action may be 4-6 hours after prolonged infusion. Labetolol, a non-selective beta-blocker, demonstrates onset in 10-20 seconds with peak activity at 5 minutes. Esmolol is an ultra-short-acting, B1-beta-blocker that has rapid onset and is quickly metabolized by nonspecific red blood cell esterases; however, esmolol primarily results in decreased heart rate and demonstrates less effect on blood pressure.

Subjects will receive a 15 mcg/kg bolus of nicardipine as needed followed by an infusion initiated at 5 mg/hr. Nicardipine may be titrated every 5 minutes, increasing 5 mg/hr and administering 15 mcg/kg bolus every minute to a maximum dose of 15 mg/hr. If systolic blood pressure (SBP) is not maintained < 140 mmHg 5 minutes after achieving the maximum dose of nicardipine, medication "failure" will be declared and rescue drug (medication to be determined per anesthesiologist discretion) will be administered. Infusions may be titrated down if SBP decreases below 90 mmHg.

Subjects will receive a 0.5 mg/kg bolus of esmolol as needed followed by an infusion initiated at 50 mcg/kg/min. Esmolol may be titrated every 5 minutes, increasing 50 mcg/kg/min and administering 0.5 mg/kg bolus every minute to a maximum dose of 200 mcg/kg/min. If SBP is not maintained < 140 mmHg 5 minutes after achieving the maximum dose of esmolol, medication "failure" will be declared and rescue drug (medication to be determined per anesthesiologist discretion) will be administered. Infusions may be titrated down if SBP decreases below 90 mmHg.

Inclusion Criteria: Adult non-pregnant patients (age ≥ 18 years) undergoing general anesthesia for elective supratentorial, infratentorial, or transsphenoidal craniotomy Exclusion Criteria: Patients under 18 years of age non-English speaking, pregnancy emergent craniotomy (including trauma) awake craniotomy active 3 vessel coronary artery disease or left main coronary artery disease advanced heart block severe aortic stenosis chronic renal failure known or suspected allergy or intolerance to a study drug or its components

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